'Bloody well done, old boy,' said O'Mara, bored again.

'Gave me this piece of rock,' Wintle continued.

And I saw his hand, upward on his knee again, opening and closing round the imaginary gift.

'Rock? ' said Ned. 'Yakov gave it to you? Do you mean music? No, you mean a geological sample of some kind.'

'When we Westerners left Akadem,' Wintle resumed, as if launching himself and us upon an entirely new story, 'we stripped ourselves of our posessions. Literally . If you'd seen our group on that last day, you would not have believed it. We'd our Russian hosts crying their eyes out, hugging and embracing, flowers on the buses, even Callow was having a weep if you can believe it. And us Westerners unloading everything we had: books, papers, pens, watches, razors, toothpaste, even our toothbrushes . Gramophone records if we'd brought them. Spare underclothes, ties, shoes, shirts, socks, everything except the minimum we needed for our decency to fly home in. We didn't agree to do it. We hadn't even discussed it. It happened spontaneously . There was some did more, of course. Particularly the Americans, being impulsive. I heard of one fellow offering a marriage of convenience to a girl who was desperate to get out. I didn't do that. I wouldn't. I'm a patriot.'

'But you gave some of your goodies to Yakov,' Ned suggested, while he affected to write painstakingly in a diary.

'I started to, yes. It's a bit like feeding the birds in the park, handing out your treasures is. You pick the one who's not getting his share and you try to fatten him up. Besides, I'd taken to young Yakov, you couldn't help it, him being so soulful.'

The hand had frozen round the empty shape, the fingertips striving to unite. The other hand had risen to his brow and taken hold of a sizable pinch of flesh.

'"Here you are, Yakov," I said. "Don't be slow in coming forward. You're too shy for your own health, you are." I'd an electric shaver in those days. Plus batteries, transformer, all in a nice carrying case. But he didn't seem to be that comfortable with them. He put them aside, sort of thing, and kept shuffling about. Then I realised he was trying to give something to me . It was this rock, wrapped in newspaper. They'd no fancy wrapping, naturally. "It's a piece of my country," he says. "To thank you for your lecture," he says. He wanted me to love the good in it always, however bad it might sometimes seem from out side. Spoke a beautiful English, mind, better than half of us . I was a bit embarrassed, frankly, if you want to know. I kept that piece of old rock for very many years. Then my wife threw it out during one of her spring-cleans. I thought of writing to him sometimes, I never did. He was arrogant, mind, in his way. Well a lot of them were. I dare say we were in our way, too. We all thought science could rule the world. Well I suppose it does now, though not in the way it was meant to, I'm sure.'

'Did he write to you?' said Ned.

Wintle wondered about this for a long time. 'You can never tell, can you? You never know what's been stopped in the post. Or who by.'

From the briefcase I passed Ned the bunch of photographs. Ned passed them to Wintle while O'Mara watched. Wintle leafed through them and suddenly let out a cry.

'That's him! Yakov! The man who gave me the rock.' He thrust the picture back at Ned. 'Look for yourself! Look at those eyes! Then tell me he's not a dreamer!'

Extracted from the Leningrad evening paper dated 5th January 1954 and reconstituted by Photographic Section, Yakov Yefremovich Savelyev as a teenaged genius.

There were other names, and Ned took Wintle laboriously through each one of them, laying false trails, brushing over his tracks until he was satisfied that in Wintle's mind at least Savelyev meant no more than the rest.

'Clever of you to hide your trump in the middle of your hand,' O'Mara remarked as, glass in hand, he walked us down the drive to the car. 'Last time I heard of Savelyev he was running their testing range in darkest Kazakhstan, dreaming up ways to read their own telemetry without everyone reading it over their shoulder. What's he up to now? Selling the shop?'

It is not often I take pleasure in my work but our meeting and the place had sickened me, and O'Mara had sickened me more than both. It is not often that I seize someone by the arm either, and have to recoil, and loosen my grip.

'I take it you have signed the Official Secrets Act?' I asked him quietly enough.

'Practically wrote the bloody thing,' O'Mara retorted, very surprised.

'Then you will know that all knowledge that comes to you officially and all speculation based upon that knowledge are in the perpetual property of the Crown.' Another legal distortion, but never mind. I released him. 'So if you like your job here, and you are hoping for promotion, and if you are looking forward to your pension, I suggest you never think of this meeting again or of any name associated with it. Thank you so much for the gin. Goodbye.'

On the journey back, with the identification of Bluebird confirmed and phoned ahead of us in word code to the Russia House, Ned remained withdrawn. Yet when we reached Victoria Street he was suddenly determined not to let me go. 'You stick around,' he ordered me, and guided me ahead of him down the basement steps.

At first glance the scene in the situation room was one of purest joy. The centrepiece was Walter, poised like an artist before a whiteboard as big as he was, drawing up the details of Savelyev's life in coloured crayons. If he had been wearing a broad-brimmed hat and smock, he could not have looked more rakish. Only at second glance did I recall my eerie apprehensions of that morning.

Around him – which meant behind him, for the whiteboard was propped against the wall beneath the clocks – stood Brock and Bob, and Jack our cypher clerk, and Ned's girl Emma, and a senior girl called Pat who was one of the mainstays of Soviet Registry. They held glasses of champagne and each of them in his different way was smiling, though Bob's smile was more like a grimace of pain suppressed.

'A lonely decider,' Walter declaimed rhapsodically. He froze a moment as he heard us, but did not turn his head. 'A fifty-year-old achiever shaking his mid-life bars, looking at mortality and a wasted life. Well, aren't we all?'

He stood back. Then skipped forward again and chalked in a date. Then took a swig of champagne. And I sensed something ghoulish and scaring about him, like make-up on the dying.

'Living at their secret centre all his adult life,' he continued gaily. 'But keeping his mouth shut. Taking his own decisions, all by himself in the dark, bless him. Getting his own back on history if it kills him, which it probably will.' Another date, and the word OLYMPIAD. 'He's the vintage year. Any younger, he'd be brainwashed. Any older, he'd be looking for an old fart's sinecure.'

He drank, his back still turned to us. I glanced at Bob for enlightenment but he was looking studiously at the floor. I glanced at Ned. His eyes were on Walter but his face was expressionless. I glanced at Walter again and saw that his breath was coming to him in defiant gasps.

'I invented him, I'm sure I did,' Walter declared, seemingly oblivious to the dismay around him. 'I've been predicting him for years.' He wrote the words FATHER EXECUTED. 'Even after they'd drafted him, the poor lamb tried so hard to be good. He wasn't sneaky. He wasn't resentful. He had his doubts but, as scientists go, he was a good soldier. Until one day – bingo ! He wakes up and discovers it's all a load of junk and he's wasted his genius on a bunch of incompetent gangsters and brought the world to the edge of ruin into the bargain.' He was writing in fierce strokes while the sweat ran down his temples: WORKING UNDER ROGOV AT 109 TESTING SITE KAZAKHSTAN. 'He doesn't know it but he's joined the great Russian male menopausal revolution of the 'eighties. He's had all the lies, he's had Stalin, the Khrushchev chink of light and the long dark of Brezhnev. But he's still got one last shot in him, one last menopausal chance to print himself on the world. And the new buzz-words are ringing in his ears: revolution from above, openness, peace,- change, courage, reconstruction. He's even being encouraged to revolt.'

He was writing faster than ever, shortwinded or not: TELEMETRY, ACCURACY. 'Where will they land?' he was asking rhetorically between gasps. 'How close will how many get to how many targets when? What's the expansion and temperature of the skin? What's gravity up to? Crucial questions and the Bluebird knows the answers. He knows because he's in charge of making the missiles talk while they go along – without the Americans hearing, which is his skill. Because he's contrived the encryption systems that dodge the American super-listeners in Turkey and mainland China. He sees all the answers in clear, before Brother Rogov fudges them for his lords and masters in Moscow. Which according to the Bluebird is Rogov's speciality. "Professor Vitaly Rogov is an arse-licking toady," he tells us in notebook two. A fair judgment. That's what Vitaly Rogov is. A verifiable, fully-paid-up, spineless, arse-licking toady, meeting his norms and earning his medals and his privileges. Who does that remind us of? No one. Certainly not our own dear Clive. So Bluebird blows his lid. He confesses his agony to Katya and Katya says, "Don't just whimper, do something." And by golly, he does it. He gives us every bloody thing he can lay his hands on. The Crown jewels doubled and re-doubled. Encryptions decrypted. Telemetry en clair . Retrospective code-breaks to help us check it out. The unbuggered head on truth, before it gets repainted for Moscow consumption. All right, he's potty. Who isn't, who's any good?' He took a last swig from his glass and I saw that the centre of his face was a crimson mass of pain and embarrassment and indignation. 'Life's a botch,' he explained, as he shoved the glass into my hand.

The next I knew, he had slipped past us up the stairs and we heard the steel doors successively open and slam shut behind him till he had reached the street.

'Walter was a liability,' Clive explained to me tersely next morning, when I bearded him. 'To us he was merely eccentric perhaps. But to others' – it was the nearest I had ever known him come to acknowledging the existence of sex. He quickly censored himself. 'I've given him to Training Section,' he continued with a return to his most frigid manner. 'He raised too many eyebrows on the other side.' He meant, on the other side of the Atlantic.